SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8699dd2406e28a560036feeb14d5f79276b9edfc33f38c72e2bf5362cee57bd3' 
  AND token = 'v3J1vs8MrdlVBMYUGq+bzpeNUa3P6XpLATOqcggT52w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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