SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a4a309fee9b2e814455f4294f8dd093e1b3d7391c500028f91c5ee63793dcf0' 
  AND token = 'X7mcI4fz7XQMcVi0FP1G8Hozr/3vj1nAHq9BUDSq3Ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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