SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '455fdaa357748958efa0241f80883e13708cfde12b6e40daf74dacea5c02046e' 
  AND token = '5NsrOEzzfuOKRDF+zSA+LHO4cwjJwRb5uG7Av8KRE2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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