SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15793d4e66a5d47e9e297f5e82817951e1fb54e165905ba1a4990ef3af655670' 
  AND token = 'SVd/OXDZUkXD2WazA7uC39AsPqawZuSEFe4rOF7GfGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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