SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4edcce92dfdaeb2d55ebe4bb9274c608fc5ff53724f2b74b18ee622a0e870f09' 
  AND token = 'JLEx6Xb2HvuIRdpkFXEKs3S2NtR3K/MkcSso3/+O+7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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