SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57918e97762953ec0b1999dcbc3f8280df7e7f6318f64e07e13b532863fb4292' 
  AND token = 'BSdtwo5BloavDTCQweDzJ6iJkKc0fKQ0E8378whlonw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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