SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4378860a4f6dbcc3bd5ef89e4b409ddae1cea8381789221694ba03fc9861fce' 
  AND token = 'Ldr3Fy9GuU2LCZ0oYimFq+RC2jd1THOnPmVFKnWShV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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