SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ff93f02920847a5a5d931ee9490fc45882da94f08d7b787b3a52f19b6f35e20' 
  AND token = '8C97KYZpJ9Q5uPB0p8AQ9vyFjnFvhum36FCsG+D1ozo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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