SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48ff238cff483a6bfb6169bc1123abb956fcd785368dbaf5bb7dc0f37821c1d6' 
  AND token = '8tJjgiKnEcOTzjAGThKQ6rfW1Hjr7H9qzgtrAqZuy/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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