SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbd780c445406975577cbd98c436b9fcc34bd868808f189336b13f9506eae386' 
  AND token = 'kTCzpcww5PicqkufrVxTty5OiUgfMXuib+iMj91QqkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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