SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d837b60dfd2681c07ed8f2b6e63a6d290f0b2de73b6b2a98bcfcdd1dc7fb58b' 
  AND token = 'gi2AvvgnpKMnl+uzkrjsqrwqBoKLnkoKTo1CW/PveyM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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