SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f3f81c9f6cf3644d5403912812a3cc38c7680902a62ecc73871aeda79dbf5b1' 
  AND token = 'x/xh53T1TounFDMRWDIxXgp8acWyCfcbjYX5Bl5gm/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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