SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75ef9d8cb0a71267656f13299d8ecd230b27e3297d631efc534665bf4800d649' 
  AND token = 'ki8+KGDeC/nmDdRlesQPmSEEucM+lucJmgB40fkWdT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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