SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ced1fc90babc709c06df225f3d8a2979817fc4a376eace5809e14b5e00a5938' 
  AND token = 'XXyTBGFFY+2RoXerKv0LO74DDsX0AHJv/g7+ZxSmmIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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