SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38ec29bbfc551854573478c0fe8bceee47cea8e7c170c47eea18687e1ad1000f' 
  AND token = 'SiWkuJK3VAK4FGGSAOmBeh+oRWogzz0QvQlMr2PGzyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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