SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9495414a7216d11681f9a0615dd0663bd81793aa94ca3ba9f3a1efb6ac49350' 
  AND token = 'FystL6NG180dDTv+Mk94zKcVBzgZ4Kxci+b8+rQqZAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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