SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb28a908678781291e3d307ac483f16314a197ea63c868fcc1a65c2abcb1502c' 
  AND token = '6MULFVMQWxD0/IS7KrCu552lcvArMutINPZVZmCbMZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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