SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d91fab290cd4322ee56b0b13dfd4eb7dc80ec8b1d83c56204ce894a397982f0' 
  AND token = 'EKSEQl+zYP05GMrwzWIYZJVpwLmAOiLiIrAm7VDkEVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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