SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '936c608029c5fc82e805fb80b5f102417a5c89bbead77e756e81c942c05c5895' 
  AND token = 'YwVqiL6Lfj0ouzcgnqAyR7SSIxx9OP+RWQl0FIyHjE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}