SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c0092964d4534adc859ded3daa2ea91affbd36cd60f56bceadde3e9693e8bc6' 
  AND token = 'DQNZwcTNVwAouPZ2ld1Nyl6Yy/PmoIlDGFcB41GnzXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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