SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14ad523fafbd4c174c23c1bf1a96e3003c3ccd3bb97a8acae77943af938a789b' 
  AND token = 'zTtjtZ4uYX3/JkfZG00TUFzxFktvyLcjaWEp8E7QSMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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