SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b1b5bbd384feb9cf3dd16101d988828733f3c431a88677d0f4e4f59c100e8c7' 
  AND token = 'hqilL+84cDLigHp1KUbBrjYIHFbihIVR/7BQ7B2h2GQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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