SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afed626d041b1441f2df2095d696a6f7ab1f98275409d69d9ddf6627e785f915' 
  AND token = 'FXAK0fl7dvR8rnK+EJnHH0pOSgLuAe68zecKc2TIyAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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