SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e8b783b569f0c1a26688a4d541676c1f19903234f5fb87fc9e6ebc52ab76a62' 
  AND token = 'CUE8Gh/7ZsnpB+0HyfSW/pLz/HevzIlhseizdmVTpFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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