SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c37b09f67e066e53cfe62ac0f79eb0f761a564b7e26e809abcba29713eb3832e' 
  AND token = 'KruZjJkDKPZK1RH2nBGftC5mMXB7V2xW7WhXppLV6D0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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