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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd61bfbad4f2c63ffcb0e7ee96d8b92d629c4ae961479ed112ae6f868259dd43d' 
  AND token = 'gPfsE5GtOvVQYR16UgISBccnfWbReK1zv4ulzgy3JGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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