SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff398c4e12626cd305227794e64f431d055d51fa2a815d15078e71ed72dc2610' 
  AND token = 'fehDUgJkOhycKyaKaPkdnh5kudLUQhjKnh8otGlSPVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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