SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2be64139a26fb03e12bd4781e9142252b1dacb457210a4d253935907075f6a48' 
  AND token = 'XAiSeKrvmsXIlpiFZwygrlLyLfnAjQJr6O3oS6Q3DDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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