SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '794ca1362f34004de5064190e63edf0e5995e1d392f76356bd1ee14a8ac4bfbf' 
  AND token = 'bl/0Aq1bMCedz6/Rzmf5lNdcHEr1HnVgRBjzFRjZnSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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