SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1f15e687c865886b772f63e2def87f53296aede1f2243f376938a40c811bbce' 
  AND token = 'RVDYJ9tRj5kJ2wQD3yaHRZ1pMWJ1G6lA/6gFOrqYUB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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