SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c730cae606fbb5c78ad619170d04d1d834a94bcf2c2dcab347475108b439a887' 
  AND token = 'gnrgSEJlTBm0nQdypoYU7R5ajxILP341kCoQ2y6GOJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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