SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd67a498b437f954286e69feed85a048c3b68dbdeb04a5ccd494847698ea595e2' 
  AND token = 'tlWCZlsWuuy8T1Pl7Zn01BozwLBpsveRZDzMAjy54UA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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