SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dcdfa4843d53b0c482a2baeeb519049d808350eb2799ee057904c08406894dd' 
  AND token = 'Oq562qEsls2p8XfySh6QQoAIbFQqmx3U/Exjm3Vd7Ks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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