SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd353aad0cd84e4b3cb37d05fd8b8d7ce4d094d189e2ae0e7d5b17629b2be476a' 
  AND token = 'NPRPdGAs+FhmyR+kYch2c8gwBBxgwZF1kwcngqgpFTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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