SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20c77bd145fe79786108087d745029020bf1cfa69d44f6968a1f9ea9ce5df2b9' 
  AND token = 'xlVdTcYl6jp+G/xA+9OIopQZFEFYUeeOP1kokLnMcpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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