SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a373f29aa4a08094af811c37bafb0da4cc649e87f96673353932f377afcec78c' 
  AND token = 'gI3zgM1U4fAoV46v+w0yTTeyGPO3KsfP91EUJk8FBpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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