SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7b665d442139bb60131204ef8760d76c5898ec20405fe2035de95070432bdfa' 
  AND token = 'FUz9rmkqckGlJJsHvPCSgid2YsOeQ3pFtMaSADJd12M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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