SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38a0f6652743ed64d69cee58f8318b167508c85daf4f63ecc1f0bb9c15b3281d' 
  AND token = 'fBAKYKFBDoXZ34zQ7S2OkUuwlDwfFMC9XqbLr2HXtlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}