SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '313b696c6e4afb083a0c8f8b70acbeb26bcac5f6abd2a89b691646db6cd11e3b' 
  AND token = '8bGBvVB2XJiFoWRelr67SEew8jvvakcomXACrheqwEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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