SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35e3fca8c1e438542d4908a78305a874c0ffcfa636b19c77b9d6439cd55dc67b' 
  AND token = 'ZWW2y7IOALqg3qJkBm7gRn4WT/jBniJSJ/mrluy2wxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}