SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb4783d9d42ffe4c591e06217ec81f5f4539b7736ad258ccce2fa43316f30b24' 
  AND token = 'U4ZqvRcJoR0MKq2Ktfq3myMA27evuL1APNjHoWSYCZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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