SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a2fccfb765ff50f6b1d0497e164de991e876e4540743281b032a794f7470d5c' 
  AND token = 'zjV/vz33mRUF3sBtM/TcPomlORgEyYB6cBMibno0Lgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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