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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6c9e0e2f101273a106b63b3ace8b84a6c3aead7a09819642db9658711ee5a20' 
  AND token = 'g+Ia3ObXszocr7jqN3Eutm5GtTPh+TaOIsqPoKMTiG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}