SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '470f588e9c96d5814d1e219f311362745776a98f955e6540cc8ffdbdd7b85658' 
  AND token = 'EiobpnQP9GP18KTPzeoOen7Yp3yumiOUygCdmSkxFyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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