SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f88c152f53edae373a0222014b09792991182b4cfe193db5a38a182ce71b550f' 
  AND token = 'kloEmG+dfNPqTKUaKwgfAhoUM++UKJh1G4CE7Nkash8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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