SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e3c001ebcb760b1f47f6b4faf00167043e395b8ec46631d16b4c5f2f8d978d2' 
  AND token = 'w2bLN9vCko+eX1kCs6MOCyWIRwCgv/uT2Z+wvoh/RNM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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