SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4e4f47e6eca275210d84cf61880a1fc9bcfc64437b24e85cc387d95a15f370e' 
  AND token = 'fXjnoAvDZ9poZswn/81aw3DJ5YfXoaQkVQNTs/KCIAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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