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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9423c83a79d468007fc7d3fdb9f50cfe3569304d70dea9104042468672bafcc8' 
  AND token = '81XFGiy29nPfFfDv4dPEAVp95CSfLuIW431fkJ30Zi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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