SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f0a20b3e88f871de8604059f094439018b26fb877c470988fe151b810d5a01f' 
  AND token = 'y3yW+xpqwwRK/Ienrpq6SKB4Kha2WPYDqfRUEKHkgYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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