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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb9b4ac1f4f5ac38d2e9a46ca979352b72644151e89f3b3c55c6f5b6045f1c04' 
  AND token = 'XyyayD8Kr7pCNxLp/XnQEkr6pLSWfWy4GdzmVjV0muc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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