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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b20b60e3a49c0dc404b711ea6f1eda3d0a364f358497546fb5a9ad348d19af21' 
  AND token = 'ELkxgfa6a5sYfG2iSEFuy6lcUYX6OtA6u3L1vjMfA5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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