SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9983058ffd2e764b99adbf42d846f1bb3507a17f748be3eb434726d356d3f97' 
  AND token = 'jlQ40InjFlEb1tuBjCFjkBOgqnV14wix1pYWOzJS+l0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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