SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '456e6b8f1ad51395139c12f6f40bf370c6dcc7d683dd09b4f1dd0b2d816386f2' 
  AND token = 'pAOTjPufYzP7gMAt3sCgvh2raGZZ0WHNZu+M0ZFzxfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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