SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b37cb5df4ed15dd4e70398730e3834a63cb886f6634b9c05a4e119f640de0722' 
  AND token = 'sOjBqfaL+LpQPUBebfrA76FYMyyn/KVcG3XyPZSIyGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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