SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5e908023c964061ffcdcb02be79e627bc274af1ec12eab1bc4c4c9c424bf28e' 
  AND token = '+9UWzB04tOFYlUPeqBRhAAAcZk4fGqF9j0EYGVZypvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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