SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a15c52e47571f3c60d603e60349fb8971cfcfbfab49dd9e6c1ae6a3e96b5a5bf' 
  AND token = 'eNORjGSYOdiInx52DrLNGDn3LZUNExlp/PK7ITBIVxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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