SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15bdf714fa2bd3346dfcd48cf956a6fb240592f831f0640722cb90fffa47740c' 
  AND token = 'HJ++TCC9YFOJ9/vYOyHwBqhMOwLltAm02uUKepexwW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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