SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a6b91035747e2a22af2f4ef9c008f76be22e62193dfbd263dfc13ffa08ccc56' 
  AND token = 'dtCmMw0IUtNtuH3J2cONvj32cCx+JDlQSFGA6Jr7gR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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