SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3786a5521176465ff2dc4d01ae30cd0141f89d62076b7580b9b7962c46bf35a' 
  AND token = 'omK3b7sLlVLLNlvoH0xgveyfhPBrGHN+bGQiu5WiPng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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